// Define the LED pin as D9 (GPIO 9 on XIAO RP2040)
#define USER_LED_PIN 9

void setup() {
  // This runs once when the board powers on or resets
  // pinMode() sets the pin mode to OUTPUT
  pinMode(USER_LED_PIN, OUTPUT);
  
  // Initialize serial communication for debugging (optional)
  Serial.begin(115200);
  Serial.println("LED Blink Program Started!");
}

void loop() {
  // This runs continuously forever
  // Turn the LED ON (set pin to HIGH = 3.3V)
  digitalWrite(USER_LED_PIN, HIGH);
  delay(1000);  // Wait 1000 milliseconds (1 second)
  
  // Turn the LED OFF (set pin to LOW = 0V)
  digitalWrite(USER_LED_PIN, LOW);
  delay(1000);  // Wait 1000 milliseconds (1 second)
  
  // The LED now blinks on and off with 1-second intervals
}